The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
It has been purported that more than 15 million tons of vulcanized rubber products are discarded throughout the world annually. This figure includes 250 million scrap tires that the U.S. Environmental Protection Agency (EPA) estimates are generated in the United States each year. Presently, the Rubber Manufacturers Association (RMA) estimates that between two and three billion scrap tires are currently in landfills or otherwise “stockpiled” in the United States alone. The handling and disposal of this large volume of waste rubber is a significant environmental problem, and the desirability of recycling waste rubber is evident.
One method of recycling waste rubber products has been to pulverize the rubber and form a rubber powder, also known as ground rubber or crumb rubber. Rubber powder is used in various ways, for example in asphalt rubber, ground cover for athletic and recreational activities, soil additives, and new rubber parts, e.g. tires. Recycled rubber is also used in joint or crack sealants. In particular, crumb rubber is used in sealing agents for water and other liquids at tube joints, roofing, point-sealing of ceramic tiles, rubber articles, and metal sheets. In many instances, the use of rubber powder in these applications is economical and results in a cost savings.
Heretofore, the use of crumb rubber in automotive coating applications has been generally limited to adhesives and protective coatings. For example, U.S. Pat. No. 6,521,706 discloses coating compositions comprising an epoxy-functional polymer and ground vulcanized rubber particles suitable for use as adhesives and corrosion inhibiting protective coatings. As disclosed in U.S. Pat. No. 5,925,466, crumb rubber has also been used in protective materials for automotive applications, such as truck bed liners.
The use of crumb rubber is advantageous from an environmental standpoint and, in many instances, is financially desirable. Accordingly, there is a continuing interest in new applications for pulverized rubber.